PROJECT SUMMARY Long term objectives and training aims: With this award, Dr. Rachel Stine will receive the support, mentorship and training required to reach her ultimate goal of becoming an independent investigator focused on the metabolic control of stem cells within the intestinal niche. This research is an excellent fit for the mission of the NIDDK as it relates to both digestive and metabolic disorders. The University of Pennsylvania offers all of the scientific resources required to complete this proposal, as well as two exemplary research programs focused on metabolic studies and intestinal biology respectively. Dr. Stine has assembled a group of renowned scientists to serve as her mentors, advisory committee and collaborators. She has developed a training plan to enhance her publication record, to secure independent funding in the form of project grants and to apply for and secure an independent position by the completion of this award. Dr. Stine?s distinctive research program seeks to answer basic questions about stem cell biology in the intestine, and will ultimately provide insight into how alterations in metabolic control of stem cells and their differentiating daughters can lead to a disease state. Dr. Stine will master techniques essential to her success in this proposal and her future independent research; integrate and expand her expertise in metabolism and intestinal biology through classes, mentorship and interactions within the broader scientific community; and build skills to successfully secure an independent position and start a new laboratory. Background and research aims: Intestinal stem cells have the capacity to rapidly divide and replenish the intestinal lining every few days. Preliminary studies completed by Dr. Stine show that deletion of the transcription factor PRDM16 in an adult mouse causes severe intestinal wasting within five days and death shortly after. RNAseq following Prdm16 deletion shows downregulation of metabolic genes in the intestinal crypt, particularly members of the fatty acid oxidation (FAO) pathway. Intriguingly, pharmacological inhibition of FAO blocks budding and growth of intestinal enteroids, specifically in the proximal small intestine where PRDM16 is highly expressed. Both PRDM16-deficiency and pharmacological inhibition of FAO can be rescued by supplementation with acetate, which can replenish pools of acetyl-CoA. Aim 1 will determine which intestinal progenitor cell populations require high levels of PRDM16 and FAO, allowing for more targeted analysis into how these pathways regulate intestinal differentiation. This aim will also explore whether mechanisms identified in mice are applicable to a human system. Aim 2 focuses on why FAO specifically is required for acetyl-CoA production, even in the presence of other nutrients. Because acetyl-CoA facilitates acetylation of histones, histone profiling as well as genetic perturbations in the acetyl-CoA pathway will be used to explore these mechanisms. This proposal will determine how metabolic changes in intestinal stem and progenitor cells translate to changes in cell behavior and provide fundamental insights into the role metabolism in this system.